Hydrocarbon conversion



Jan. 25, 1944. c. 1.. THOMAS 2,339,918

HYDROCARBON 'CONVERS ION Filed Sept. 13, 1940 FRACTIONATOR IN REACTION Z JS CHAMBER SEPARATING FURNACE FURNACE 38 TOR v REACTOR FURNACE 7 INVENTOP.

CHARLES L. THOMAS ATTORNEY Pmma Jan. 25, 1944 HYDROCARBON CONVERSION Charles L. Thomas, Chicago, 111., asslgnor to Uniyersal Gil Products Company, Chicago, IlL, a corporation of Delaware Application September 13, mt, Serial No. 358,596

6 Claims.

This is a continuation-in-part Of my co-pending applications, Serial Numbers 291,889 and 291,890, flled August 25, 1939.

This invention relates to a process for the conversion of hydrocarbon oil into substantial yields of gasoline and more specifically to an improved process combining catalytic with thermal cracking wherein charging oil and selected insufficient- 1y converted hydrocarbons from both thermal and catalytic cracking are subjected to catalytic cracking and the residual portion of the insufflciently converted hydrocarbons from both thermal and catalytic cracking are subjected to thermal cracking.

Catalytic cracking as ordinarily conducted does not employ ecycling of insufliciently converted products to the conversion zone because, as has been found, such insufllciently converted hydrocarbons contain a certain amount of undesirable material, the tendency of which is to deposit great amounts of carbon or carbonaceous substances upon the catalyst particles if recycled to the catalyst zone resulting in a more rapid lowering of catalyst activity than is encountered when passing clean unconverted oils in contact with such catalysts. In order to reduce the formation Of carbonaceous substances during con version, resulting in shorter reactivation times and lower peak reactivating temperatures, it is usual to pass the hydrocarbon oil in contact with the catalyst only once and then thermally crack the insufllciently converted oils in a thermal cracking system. In a process employing both thermal and catalytic cracking in the manner above mentioned, the yield and octane of the gasoline product 'is good but is not as good as carbons separated from th thermally formed re-' action products and a portion of the light insufflciently converted hydrocarbons separated from the catalytically formed reaction products is subto thermal treatment. Preferably also, the conditions of temperature and 'pressure employed in the thermal treatment are selected to favor the removal of carbon forming constituents present in the insufllciently converted hydrocarbons from catalytic cracking and to produce lighter hydrocarbons other than gasoline from the heavy in-.

sufliciently converted hydrocarbons rather than cracking to gasoline, although some of the latter may occur. By this method, compounds undesirable in catalytic cracking, because of their tendency to form carbonaceous substances which are present in relatively large amounts in the insufliciently converted hydrocarbons, undergo some treatment which converts them into higher boiling hydrocarbons whereby the may be removed as liquid residue in the vaporizing and separating step of the thermal treating system.

In one specific embodiment th invention comprises passing hydrocarbon vapors, including vaporized charging oil and vaporized insufllciently converted hydrocarbons formed in the manher to be described, in contact with a mass of cracking catalyst, fractionating the conversion products to separate fractionated vapors, light reflux condensate and heavy reflux condensate, returning a portion of said light reflux condensate to the catalytic conversion step, commingling the residual portion of said light reflux condensate with said heavy reflux condensate and subjecting the mixture to thermal treatment, commingling the reaction products from said thermal treatment with reaction products formed in a separate thermal treatment as hereinafter set forth and passing the mixture through an elongated reaction chamber wherein substantial further reaction occurs, separating the resulting thermal reaction products into non-vaporous liquid residue and vaporous reaction products, fractionating said vaporou reaction products to separate fractionated vapors, light insufliciently converted hydrocarbons, and heavy insufliciently converted hydrocarbons, returning said light insufllciently converted hydrocarbons to the catalytic conversion step, subjecting said heavy insumciently converted hydrocarbons to thermal treatment and commingllng the reaction products from the last mentioned thermal treatment with those formed in the first mentioned thermal treatment as hereinbefore set forth.

In another embodiment of the invention the heavy reflux condensate from catalytic cracking and the residual portion of the light reflux condensate not returned to the catalytic conversion treatment may be commingled with the heavy insufliciently converted hydrocarbons from the thermal cracking step and the combined mixture subjected to thermal treatment under conditions selected to favor both thermal cracking of the heavy material into lighter hydrocarbons and the desired thermal treatment of the insuiliciently converted hydrocarbons from catalytic cracking a to remove to a large extent carbon forming substances.

The invention specifically contemplates subjectlng allofthecharging ilto catalyt c cracking. because it has been found that although the charging oil may and usually does contain hydrocarbons boiling above those present in the insufllciently converted hydrocarbons subjected to catalytic cracking, carbon formation is usually not as heavy as would be obtained if the insuillciently converted hydrocarbons from catalytic cracking or the heavy insumciently, converted hydrocarbons from thermal cracking are returned to the catalytic cracking step. Decreased carbon formation is exceedingly advantageous in shorteningthe time required for reactivating the catalytic material and as a means for decreasing peak reactivating temperatures and consequently the amount of heat generated valve 2 to pump 3. Pump 8 discharges through line 4 containing valve I after which the oil is commingled with light insumciently converted hydrocarbons separated in the manner to be described and the mixture introduced to heating coil 8 which receives heat from furnace I. When desired, steam and/or light gaseous hydrocarbons, the latter comprising either those formed in the process or light gases introduced from an exterior source are commingled with the mixtureofhydrocarbonoilinlinelto aidinsubstantially completely vaporizing the hydrocarbon oil supplied to heating coil and also as a means for reducing the total pressure on the hydrocarbon oil. In any event, the mixture supplied to heating coil 8 is substantially completely vaporized therein and heated to a temperature ranging. for example, from 800 to l200 I". prefer- -ably while being maintained under a pressure Ir 8 8. for example, from substantially atmospheric to 200 pounds or more per square inch. The heated reactants leaving coil t are directed through line i containing valve 0 into reactor is which contains catalytic material capable of exterior of said elongated tubular elements whereby to supply heat to the reactants during conversion and to effect cooling during reactivation of the mass of catalytic material. II, on

- tially in the range of gasoline from the higherthe other hand, may comprise a cylindrical vessel which is well insulated to reduce radiation losses and which contains one or a plurality of beds of catalytic material wherein the reaction may be accomplished substantially adiabatically.

In the catalytic cracking of hydrocarbons relatively large amounts of carbonaceous substances are formed which deposit upon the catalytic material thereby reducing its active surface and necessitating reactivation at periodic frequent intervals. The invention contemplates reactivatingtheusedcatalytic materialintheusualmanner, such as, for example, by passing oxygencontaining reactivating gases in contact with the used catalytic material and removing carbonaceous substances as combustion gases along with the spent reactivating gases. It is desirable.

therefore, in order that the operation may be carried out as a continuous process to employ at least two reactors and in some instances more than two reactors so that while the catalytic material in one reactor is being usedfor effecting conversion of the hydrocarbon reactants the catalytic material in the other or others may be undergoing reactivation.

Catalysts which have been found to be elective in the catalytic cracking of hydrocarbon vapors may comprise pellets or granules of silica or other siliceous and refractory materials composited with compounds selected from the group consisting of alumina, zirconia, and thoria. In addition. the hydrosilicates of alumina, acid treated clays, or the like, have also'been found to be effective in the cracking treatment of hydrocarbon vapors. Although the catalysts above recited are generally considered to be preferred catalysts their use is not to be construed as a limiting feature, for variousother catalysts well known to those in the art may be employed within the broad scope of the invention.

The conversion products, leaving reactor II are directed'through line H containing valve l2 into fractionator it which, together with the condensing and collecting equipment in communication therewith, may be operated under a superatmospheric pressure ranging, for example, from substantially atmospheric to 200 pounds or more per square inch. The conversion products supplied to fractionator II are fractionated therein .to separate fractionated vapors boiling substanboiling insufficiently converted hydrocarbons, the latter being condensed in the fractionator and further separated therein into light insuiilciently converted hydrocarbons and heavy insuillciently converted hydrocarbons, the light insuiliciently converted hydrocarbons preferably. comprising those boiling below 650 1". while the heavy insufficientl converted hydrocarbons include all the insufliciently converted hydrocarbons boiling above said light insufilciently converted hydrozcarbons.

Fractionated vapors separated in fractionator it are directed through line it containing valve ll tocooling and condensation in condenser It. Distillate, together with undissolved and uncon-.

densed gases in condenser It. is directed through line l'l containing valve ll into receiver II wherein the distillate and undissolved and uncondensed gases are collected and separated.- Undissolved and uncondensed gases separated in receiver it are removed by way of line 2. containing valve II and may be recovered as a product of the process or as above mentioned a portion thereof may be commingled with the charging oil for use in the manner previously described. A portion of the distillate collected and separated in.

receiver l3 may be returned to the upper portion of fractionator II by well known means, not shown, as refluxing and cooling medium while the residual portion thereof is removed from receiver l9 by way of line 22 containing valve 23 and recovered as a product of the process or subjected to any desired further treatment.

Light insufliciently converted hydrocarbons separated in fractionator l3 are directed through line 24 containing valve 25 to pump 25. Pump 26 discharges through line 21 and all of the light insufficiently converted hydrocarbons may be directed through line 28 containing valve 23 into line 34 where they commingle with the heavy insumciently converted hydrocarbons removed from fractionator II in the manner to be described. Preferably, however, at least a portion of the light insufliciently converted hydrocarbons in line 21 is directed through valve 30, commingling with the charging oil in line 4 for treatment in the manner previously described. In some instances, the volume of light insufflciently converted hydrocarbons, separated in fractionator l3, returned-to the catalytic cracking step, may be substantially equal to the volume of charging oil with no undue amount of carbon deposition. However, it is usually desirable to return less of light insufficiently converted hydrocarbons than the volume above mentioned to catalytic cracking and subject the greater portion thereof to thermal treatment in the manner to be described. The heavy insuficiently converted hydrocarbons separated in fractionator l3 are directed through line 3| containing valve 32 to pump 33. Pump 33 discharges through line- 34 containing valve 35 and the heavy insufilciently converted hydrocarbons are commingled with the light insufliciently converted hydrocarbons diverted through line 28 and valve 29 in the manner previously described, the mixture beingdirected through valve 36 into heating coil 31 which receives heat from furnace 38. In some cases, however, instead of using a separate heating coil for treating the insufflciently converted hydrocarbons from fractionator l3, the mixture in line 34 may be directed through line 39 containing valve 40 into line 10, after which it may be subjected to treatment in commingled state with line 45 are directed through valve 46- and when a heating coil 37 is employed are commingled with heavy reflux condensate separated in the manner to be described.

When heating coil 37 is employed, the insufliciently converted hydrocarbons in passing therethrough are subjected to temperature and pressure conditions selected to favor reactions which tend to convert the undesirable carbon forming constituents contained therein into heavier hydrocarbons which are removed from the process as liquid residue in the manner to be described.

Temperatures to which the insufliciently con-' verted hydrocarbons may be heated in coil 3l-will fall within the range of 800 to 1000" F. while employing a superatmospheric pressure ranging, for example, from 100 to 1000 pounds or more per square inch.

The heated products leaving coil 31 are directed through line 4| containing valve 42 into line 45 where they commingle with the conversion products formed in the manner to be described. Heavy reflux condensate separated in the man'- ner to be described is introduced to heating coil 43 which receives heat from furnace 44. When desired, as above mentioned, the heavy reflux condensate may be commingled with the insuffithe heated products from that coil in the manner previously described. The reaction products in line 45 are then introduced to reaction chamber 41 wherein the conversion reaction instigated in the heating coil proceeds to a proper degree of completion. Reaction chamber 41, in the case here illustrated, is preferably operated under a superatmospheric pressure substantially the same or slightly less than that employed in the communicating heating coil and preferably also is insulated to reduce radiation losses therefrom, although no insulation appears in the drawing.

Reaction products leaving reaction chamber 41 are directed through line 48 containing valve 49 into vaporizer and separator 50. When desired, the use of reaction chamber 4! may be obviated by providing sufficient soaking time in the communicating heating coils to allow the reaction to'proceed to the proper degree of completion and introducing the reaction products from these heating coils directly to vaporizing and sep-' arating chamber 50 and since the means for accomplishing this are well known, such means are not illustrated.

vaporizing and separating chamber50 is preferably operated at a reduced pressure relative to that employed in the reaction chamber and/or the heating coils which may range,- for example, from substantially atmospheric to 200 pounds or more per square inch. Vaporous reaction products are separated from the non-Vaporous liquid reaction products in chamber 50 and the latter substantially further vaporized to form a nonvaporous liquid residue which is removed from chamber 50 by way of line 5i containing valve 52, recovered as a product of the process or subjected to any desired further treatment.

Vaporous reaction products, including vapors evolved within chamber 50, are directed through line 53 containing valve 54 into fractionator 55. Fractionator 55, together with condensing and collecting equipment in communication therewith, is preferably operated at a pressur substantially equal to that employed in chamber 50. Vaporous reaction products supplied to fractionator 55 are fractionated therein to separate fractionated vapors boiling substantially in the range of gasoline from the higher boiling reaction products and the latter condensed as light and heavy reflux condensate. Light reflux con- .densate separated in fractionator 55 preferably therefrom by way of line I: containing valve 08, recovered as a product of the process or subjected to any desired further treatment. A portion of the distillate collected and separated in receiver ll is returned to the upper/portion of fractionator II by well known means, not shown,

as a refluxing and cooling medium while the residual portion thereof is removed from receiver I by way of line containing valve ll, recovered as a product of the process, subjected to stabilisation or to any desired further treatment.

Heavy reflux condensate separated in fractionator It is directed through line 88 containing valve 01 to pump 00. Pump It discharges through valve 00 and line into heating coil 0 and, as above mentioned, prior to the introduction of the heavy reflux condensate to heating coil 03; it may be commingled with the insufllciently converted hydrocarbons from fractionator it. Light reflux condensate separated in fractionator II is directed through line Ii containing valve 12 to pump 13 which discharges through line H containing. valve Ii into line 4 where said light reflux condensate commingles with the charging oil for treatment in the manner previously described.

An example of one specific operation of the process as it may be accomplished in an apparatus such as illustrated and above described is approximately as follows: Charging oil comprising 'a. 33 A. P. I. gravity Mid-Continent gas oil is commingled with light insufliciently converted arated as above mentioned are condensed in the iractionator and separated into light insufliciently converted hydrocarbons and heavy lnsufliciently converted hydrocarbons, A portion of the light insumciently converted hydrocarbons approximately equal in volume to the charging oil issupplied to-the catalytic conversion step while the residual portion-thereof is commingled with the heavy insufliciently converted hydrocarbons and the mixture subjected to non-catalytic thermal treatment at a temperature of 850 F. and a superatmospheric pressure 0! 300 pounds per square inch. The reaction products leaving the last step are commingled with other reaction products formed in a separate non-catalytic thermal treatment in the manner to .be described and the mixture supplied to a vaporizing and separating chamber operated at a superatmospheric pressure of approximately pounds per square tionator as light and heavyreflux condensate and the light reflux condensate supplied to the catalytic conversion step. The heavy reflux condensate is subjected to thermal treatment separate from the flrst mentioned thermal treatment at a temperature of 920 F. and at a superstmospheric pressure of 300 pounds per square inch and the reaction products resulting therefrom commingled with the flrst mentioned reaction products in the manner previously described.

From an operation employing conditions as above mentioned one may obtain approximately 45.2% of 4001". catalytically cracked gasoline having an octane rating of 80, approximately 22.9% of 400 1". thermally cracked-gasoline of 69 octane rating, 20.0% of liquid residue of 8 A. P..l. gravity, the balance being principally carbon, gas, and loss.

I claim as my invention: 7

l. A process for the conversion of hydrocarbon oil which comprises passing vapors of said hydrocarbon oil at a cracking temperature in coninch. Non-vaporous-liquid residue is separated from the vaporous reaction products in the vaporizing and separating chamber and the liquid residue recovered as a product of the process.

The vaporous reaction products separated as above mentioned are fractionated to separate fractionated vapors of approximately 400 1 end point from the higher boiling reaction products. The fractionated vapors are subjected to cooling and condensation and the resulting distillate and,

gas collected and separated. The higher boiling reaction products are condensed in the fractact with a mass of cracking catalyst. fractionating the conversion products to separate fractionated vapors, light insufliciently converted bydrocarbons, and heavy insufliciently converted hydrocarbons, supplying a portion of said light insufllciently converted hydrocarbons to the catalytic conversion step, commingling the residual portion of said light insufliciently converted hydrocarbons with said heavy insumciently converted hydrocarbons and subjecting the mixture to non-catalytic thermal treatment, separately i'ractionating vaporous reaction products from said non-catalytic thermal treatment to sepaand heavy reflux condensate. supplying said light reflux condensate to the catalytic conversion step and said heavy reflux condensate to the noncatalytic thermal treatment, and finally condensing the fractionated vapors.

2. A process for the conversion of hydrocarbon oil which comprises passing vapors of said hydrocarbon oil at a cracking temperature in contact with a mass of cracking catalyst, fractionating the conversion products to separate fractionated vapors, light insufliciently converted hydrocarbons, and heavy insufllciently converted hydrocarbons, supplying a portion of said light insuiliciently converted hydrocarbons to the catalytic conversion step, commingling the residual portion of said light insufllciently converted hydrocarbons with said heavy insufllciently converted hydrocarbons and subjecting the mixture to noncatalytic thermal treatment, separately fractionating vaporous reaction products from said noncatalytic thermal treatment to separate fractionated vapors, light reflux condensate, and heavy reflux condensate; supplying said light reflux condensate to the catalytic conversion step, subjecting said heavy reflux condensate to a non- -catslytic thermal treatment separate from the flrst mentioned thermal treatment and fractionating the vaporous reaction products from the last mentioned thermal treatment in comminsled state with the vaporous reaction products from the flrst mentioned thermal treatment, and finally condensing the fractionated vapors.

3. A process for the conversion of hydrocarbon oil which comprises passing vapors of said hl ocarbon oil at a cracking temperature in contact with a mass of cracking catalyst, fractionating the conversion products to separate fractionated vapors, light insufliciently converted hydrocarbons having an and boiling point not rate fractionated vapors, lightreflux condensate,

substantially in excess of 650 F. and heavy insumciently converted hydrocarbons containing ing an end boiling point not substantially in excess of 650 F. and heavy reflux condensate containing the fractions of said vaporous reaction products boiling above 650 F., supplying said light reflux condensate to the catalytic conversion step, subjecting said heavy reflux condensate to a non-catalytic thermal treatment separate from the first mentioned thermal treatment and fractionating the vaporous reaction products from the last mentioned thermal treatment in comlyticthermally formed vaporous reaction products, separately iractionating said vaporous reaction products to separate fractionated vapors, light reflux condensate, and heavy reflux condensate, supplying said light refluxoondensate to the catalytic conversion step and said heavy reflux condensate to the non-catalytic thermal treatment, and finally condensing the fractionmingled state with the vaporous reaction products from the first mentioned thermal treatment,

and finally condensing the fractionated vapors.

4. A process for the conversion of hydrocarbon oil which comprises passing vapors of said hydrocarbon oil at a cracking temperature in contact with a mass of cracking catalyst, fractionating the conversion products to separate fractionated vapors, light insufllciently converted hydrocarbons, and heavy insufllciently converted hydrocarbons, supplying a portion of said light insufficiently converted hydrocarbons to the catalytic,

conversion step, commingling the residual portion of said light insufliciently converted hydrocarbons with said heavy insufilciently converted hydrocarbons and subjecting the mixture to noncatalytic thermal treatment in a heating coil and communicating reaction chamber, separating non-vaporous liquid residue from the non-cataated vapors.

5. The process defined in claim 4 further characterized in that the heavy reflux condensate is subjected, to thermal treatment in a separate heating coil and the reaction products thereafter commingled with the reaction products formed in the thermal treatment of the insufllciently converted hydrocarbons from the catalytic cracking step prior to their introduction to the reaction chamber.

6. A process for the conversion of hydrocarbon oil which comprises passing vapors of said hydro= carbon oil at a cracking temperature in contact with a mass of synthetically prepared silicaalumina-zirconia catalyst, fractionating the con-- version products to separate fractionated vapors, light insufficiently converted hydrocarbons, and

heavy insufllciently converted hydrocarbons, sup plying a portion of said light insufiiciently converted hydrocarbons to the catalytic conversion step, commingling the residual portion of said light insufliciently converted hydrocarbons with said heavy insumciently converted hydrocarbons and subjecting the mixture to non-catalytic thermal treatment, fractionating vaporous reaction products from said non-catalytic thermal treatment to separate fractionated vapors, light reflux condensate, and heavy reflux condensate,

supplying said light reflux condensate to the catalytic conversion step and said heavy reflux condensate to the non-catalytic thermaltreatment, and finally condensing the fractionated vapors.

CHARLES L. THOMAS. 

